Psychometric properties of the Physical Activity Scale for the Elderly in Chinese patients with COPD

Background: For patients with COPD, physical activity (PA) is recommended as the core component of pulmonary rehabilitation, but there is lack of a validated questionnaire for assessing the PA effectively. Aim: To evaluate the reliability and validity of the Chinese version of Physical Activity Scale for the Elderly (PASE-C) in patients with COPD. Methods: A cross-sectional study was conducted with 167 outpatients aged 60 years or older with COPD. Test-retest reliability and internal consistency were calculated by intraclass correlation coefficient (ICC) and Cronbach's coefficient alpha, respectively. Validity was evaluated by correlation with the International Physical Activity Questionnaire-Short (IPAQ-S), data of pedometer, Self-Efficacy for Managing Chronic Disease 6-Item Scale (SES6), Hospital Anxiety and Depression Scale (HADS), Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), grip strength, and disease characteristics. Results: The PASE-C had an excellent seven-day test-retest reliability (ICC=0.98) and an acceptable internal consistency (Cronbach's alpha=0.71). The content validity was supported by an item-content validity index, a scale-content validity index/universal agreement, and a scale-content validity index/average value of 0.70-1, 0.70, and 0.93, respectively. Concurrent validity was tested by correlation with IPAQ-S (r=0.651). Criterion validity was confirmed by correlation with the walking steps (r=0.611) and energy expenditure (r=0.493). For construct validity, PASE-C had correlations with SES6 (r=0.396), HADS for depression (r=-0.234), seven subscales of SF-36 (r=0.182-0.525), grip strength (r=0.341), and disease characteristics including the duration of COPD (r=-0.215), modified British Medical Research Council scale (r=-0.354), forced expiratory volume in one second as percentage of predicted (r=0.307), and Global Initiative for Chronic Obstructive Lung Disease grade (r=-0.264), with a good construct validity (all P<0.05). Conclusion: The PASE-C has acceptable reliability and validity for patients aged 60 years or older with COPD, and it can be used as a valid tool to measure the PA of patients with COPD in the People's Republic of China.